Implementing an invmap function on SwiftUI's Binding type.

BindingInvmap.swift

import SwiftUI

extension Binding {

    func invmap<NewValue>(
        to: @escaping (Value) -> NewValue,
        from: @escaping (NewValue) -> Value
    ) -> Binding<NewValue> {

        Binding<NewValue>(
            get: { to(wrappedValue) },
            set: { wrappedValue = from($0) }
        )
    }
}

var tuple: (Int, String) = (1, "A")
let tupleBinding = Binding(get: { tuple }, set: { tuple = $0 })

struct Foo {
    let int: Int
    let string: String
}

let fooBinding = tupleBinding.invmap(to: Foo.init,
                                     from: { ($0.int, $0.string) })

print("Before", tuple)
fooBinding.wrappedValue = Foo(int: 2, string: "B")
print("After", tuple)